Leukoaraiosis (LA) refers to neurodegenerative white matter changes that are associated with
age and appear as areas of hyperintensity on magnetic resonance imaging (Hachinski, Potter,
and Merskey, 1987). Leukoaraiosis has been associated with cognitive impairment and
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vascular risk factors in nondemented elderly (DeCarli et al., 1995; deGroot et al., 2000),
while the relationship with demented elderly is unclear. The current study examined the
severity of LA, the relationship between vascular risk factors and LA, and associations
between neuropsychological functioning and LA across three groups with varied levels of
cognitive functioning. Total LA was more severe among subjects with Alzheimer’s Disease
(AD, n = 30) than those with Mild Cognitive Impairment (MCI, n = 30) and nondemented
elderly (NE, n = 30), but MCI did not have more severe LA than NE. Periventricular and
subcortical LA were more severe in AD than MCI, but not NE. Age was a significant
predictor of both periventricular and subcortical LA, but hypertension and homocysteine
were not independently related to LA. Total LA was inversely associated with
neuropsychological performance for all subjects, though correlations were low to moderate (r
= -.23 to r = -.36), and were not significant after controlling for the effects of age and
cerebral atrophy. Within the AD group, several significant positive correlations between LA
and neuropsychological measures emerged, but were reduced when controlling for age, but
not atrophy. Results for periventricular LA were similar to total LA findings, while
subcortical LA had fewer correlations with neuropsychological measures.
Neuropsychological measures of general cognitive functioning, verbal fluency, memory, and
executive functioning were associated with increased total and periventricular LA, while
measures assessing confrontation naming, visuoconstructional ability, and attention were less
affected. Across all subjects, age and cerebral atrophy contributed to associations between
neuropsychological performance and LA. Despite greater atrophy and LA in the AD group,
neuropsychological functioning was not associated with increased LA within the AD group
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in the current study. This suggests that relationships between LA and neuropsychological
functioning may be identifiable in normal controls, but that disease characteristics play a
larger role in cognition in dementia populations such as Alzheimer’s disease.
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